1. Field of the Invention
This invention relates to rotary coolers for cooling hot loose bulk material with cool air.
2. Prior Art
Hot, loose bulk material, particularly iron ore sinter, is cooled in rotary coolers by means of introduced cool air. The coolers have a cooling chamber which is bounded on the inside and the outside by walls permeable to gas. The cool air is introduced under pressure through the inner wall, blown through the loose material and exits through the outer wall. The cooling chamber can be formed either of circular individual cells arranged next to one another or between two ring walls arranged concentric to each other. The hot loose material is placed in the cooling chamber from above and removed by a pick-off as cooled material from the bottom plate of the cooler. With horizontal conduction of the cool air, the layer thickness of the material is limited by the pressure used, while the height of the material is a function only of the limit of the allowable wheel load. These coolers therefore require relatively little ground surface. Such coolers have been described in U.S. Pat. Nos. 3,168,384 and 2,681,158, and German patent publications AS 1,964,323, OS 2,005,928, AS 1,963,936, which use one or two circular cooling chambers. These coolers are run from a central bearing and require a supporting structure from the inside. Moreover, the cooling chambers are firmly integrated in the supporting structure, whereby thermal stresses are transferred to the support structure and cause slight deformities therein, and the support structure undergoes great wear from mechanical friction on the parts which come in contact with the material in motion.
Even on round coolers with bottom emptying of the cooling chamber, central operation is accomplished either by a center bearing or else there are two rails with flanges, which are subject to great wear and which place great loads, especially on the wheel bearings (German patent publications PS 1,025,916, AS 1,041,513, AS 1,145,196, AS 1,173,662).
For round coolers, in which the cooling air is blown in through a bottom permeable to gas -- which, therefore, must be operated with a low material layer thickness -- it is also known that the central operation of the cooler is done with horizontal contact rollers, which run on a horizontal circular track. These coolers have bottom and side emptying, and must be braced on two concentric rails with tread rollers, and the gas-permeable bottom is an integral part of the support construction.
From German patent publication PS 1,133,557 for round coolers with bottom emptying and from German patent publication OS 1,926,753 for round coolers with pick off emptying of the material from a bottom plate it is shown that the cooling chamber is formed by cells located next to each other, so that the cells are movably fastened to the supporting construction. Thus no heat stresses are transferred to the support construction, these types undergo no wear from the material to be cooled. The support apparatus, however, overstresses the inner room of the cooler.
A round cooler is shown by German patent publication OS 1,944,669, on which the outer wall of the cooling chamber moves freely on the bottom plate and thus transfers no heat stresses to the support construction. The central operation is done with a central bearing and the support apparatus overstresses the inner space of the cooler.
The purpose of the invention is to eliminate the disadvantages of the round coolers demonstrated with emptying by picking off the material from the bottom plate and especially to manage to have the inner space free of the support construction, to protect the support construction from heat stresses and abrasive wear from the material to be cooled, and to keep the construction of the cooler simultaneously as light and as static as possible.